The field of the disclosure relates generally to rotor blades for rotary machines, and more particularly to a rotor blade having cooling passages defined in a tip shroud of the blade.
At least some known rotor blades include tip shrouds. For example, the tip shrouds improve an aerodynamic performance of the rotor blades. In addition, at least some known rotor blades are subject to wear and/or damage from exposure to hot gases in a hot gas path of a rotary machine. Thus, at least some known rotor blades include a plenum defined in the tip shroud, and cooling fluid is supplied to the plenum and exhausted through a peripheral edge of the tip shroud during operation of the rotary machine to cool the tip shroud and/or other portions of the rotor blade near the tip shroud. However, for at least some known rotor blades, diversion of the cooling fluid internally through the periphery of the tip shroud reduces an amount of cooling fluid available for film and/or convection cooling of a radially outer surface of the tip shroud.
Moreover, an amount of cooling needed varies for different regions on or proximate the tip shroud, and an amount of cooling fluid supplied to the plenum is selected to accommodate the portion with the greatest cooling needs. For at least some known rotary machines, supplying a larger amount of cooling fluid to the rotor blade simultaneously decreases an efficiency of the rotary machine. Alternatively or additionally, to reduce an amount of cooling fluid needed for the tip shroud, at least some rotor blades are formed with an increased “scallop” of the tip shroud, such that a distance that the tip shroud extends perpendicular to an airfoil of the rotor blade is decreased. However, for at least some rotary machines, increasing the scallop of the tip shroud also reduces an aerodynamic effectiveness of the tip shroud, thereby decreasing an efficiency of the rotary machine.